Northward and eastward expansion of the range of coyote (Canis latrans) in North America has been associated with an increase in body size, although documentation is limited. In this study, published weights of coyotes from various geographic areas and new data from the Kenai Peninsula, Alaska, were found to differ by sex (P < 0.001) and longitude (females, P = 0.036; males, P = 0.017), but not latitude (females, P = 0.861; males, P = 0.302). Significant longitudinal variation was attributable to the large size of coyotes in New Hampshire. We suggest that phenotypic response to food supply may account for most variation in body size of coyotes.